There are several in the Joe Grey series, in case you haven't read them all. Here are a few other suggestions:

The Cat Who Could Read Backwards by Lilian Jackson Braun.
Reporter Jim Qwilleran is so anxious to get back to work that he accepts a job covering the art world for the Daily Fluxion. When various people turn up dead, only Qwilleran and his "partner," Koko, the Siamese cat, can find the answers. There are about 20 books in this series now-so if you like this first one, there are many others to keep reading!

Since you enjoyed The Prophet of Yonwood by Jeanne DuPrau, I am sending you some titles that I hope you will like just as much.

Countdown to the Year 1000 / by K.H. McMullan.
Alarmed by a prophecy that the world will end with the arrival of the
year 1000, the students of Dragon Slayers' Academy get some advice from Zack, a boy who has traveled back from 1999.

The Preacher's Boy : a novel / by Terry Pringle.
Relates the experiences of a young man growing up in a small Texas town in the shadow of his strict preacher father.

Here are some other books that I hope you will like. Like
Sandry's Book, all of these are stories have magic and friendship in
them.
If you haven't read the three books by Tamora Pierce that come after
Sandry's Book, I'd definitely recommend the rest of the Circle of Magic quartet:

The Secret of Platform 13 by Eva Ibbotson.
Odge Gribble, a young hag, accompanies an old wizard, a gentle fey, and a giant ogre on their mission through a magical tunnel from their Island to London to rescue their King and Queen's son who had been stolen as an infant.

A Wrinkle in Time by Madeline L'Engle.
Meg Murry and her friends become involved with unearthly strangers and a search for Meg's father, who has disappeared while engaged in secret work for the government.

The Extraordinary Adventures of Alfred Kropp by Rick Yancey.
Through a series of dangerous and violent misadventures, teenage loser Alfred Kropp rescues King Arthur's legendary sword Excalibur from the forces of evil.

The Mysterious Benedict Society by Trent Lee Stewart.
After passing a series of mind-bending tests, four children are selected for a secret mission that requires them to go undercover at the Learning Institute for the Very Enlightened, where the only rule is that there are no rules.

Here are some other fantasy/sci-fi/paranormal
books that you might like (some have a bit of romance in them).

A Great and Terrible Beauty by Libba Bray.
After the suspicious death of her mother in 1895, sixteen-year-old Gemma returns to England, after many years in India, to attend a finishing school where she becomes aware of her magical powers and ability to see into the spirit world. If you like this one, it is part of a series - #2 is Rebel Angels and #3 is The Sweet Far Thing.

Here are some books you might like. All of them have some romance in them, and they are all books I've enjoyed.

The Truth About Forever by Sarah Dessen.
The summer following her father's death, Macy plans to work at the
library and wait for her brainy boyfriend to return from camp, but
instead she goes to work at a catering business where she makes new
friends and finally faces her grief.